1. Field of the Invention
The present invention relates to a layout editor and its text generating method, and more particularly to a layout editor and its text generating method for use in semi-custom design or full-custom design in the mask design of IC.
2. Description of the Related Art
Generally, a net-driven tool is on the assumption of automatic wiring in many cases. In the other words, the tool itself needs no text and thereafter it has no function of text generation. A text is generally generated by user's input depending on the necessity in case of examining the wiring configuration with reference to the halfway results, or executing a work to be continued to another layout area, a layout-circuit comparison in the verification, or data modification. This kind of conventional text generating method has a data base-storing area including a graphic table for storing graphical information, a connection table for storing connection information, a correspondence table for storing the correspondence between the connection information and the graphical information, in the net-driven layout data base.
FIG. 23 is a flow chart showing the procedure of the text generating method by the conventional layout editor. With reference to FIG. 23, a first signal of the connection table is taken out from a temporary area SIG for processing a signal name taken out from the connection table (Step 2301). A temporary area SVP for correspondingly processing the signal taken out from the correspondence table is extracted (Step 2302). In this case, a temporary area SVP first detected in the correspondence table is adopted because a plurality of temporary areas SVPs exist in the correspondence table of one temporary area SIG. The coordinates of origin of a temporary area POL for processing the graphic corresponding to the temporary area SVP are extracted from the graphic table included in the data base-storing area, according to the adopted corresponding temporary area SVP (Step 2303). A text is generated on the origin of this temporary area POL (Step 2304). Here, a text for one temporary area SIG is generated at one position. Generally, when the path of a temporary area SIG is complicated and there exist a plurality of temporary areas SVPs corresponding to the temporary area SIG (for example, 50 and the more), it is difficult to know where the text exists and therefore it is very difficult to recognize the signal name by the text with eyes. It is judged whether the temporary area SIG is the last signal of the connection table or not (Step 2305). When it is not judged that the temporary area SIG is the last signal of the connection table, the next signal of the connection table in the temporary area SIG is taken out (Step 2306), the above processing will be repeated until when it is judged that the temporary area SIG is the last signal in Step 2305, and thereafter the processing will be stopped.
FIG. 24 is a flow chart showing another procedure of the text generating method by the conventional layout editor. With reference to FIG. 24, a temporary area SVP first retrieved from the correspondence table is taken out and adopted as the first temporary area SVP of the correspondence table (Step 2401). The coordinates of origin of a temporary area POL for processing the graphic corresponding to a temporary area SIG, according to the first temporary area SVP, is extracted from the graphic table included in the data base storing area (Step 2402). A text is generated on the coordinates of the origin of the temporary area POL and a text for one temporary area SIG is established at one position (Step 2403). Generally, when the path of a temporary area SIG is complicated and there exist a plurality of temporary areas SVPs corresponding to the temporary area SIG for example, 50 and the more), it is difficult to know where the text exists and therefore it is very difficult to recognize the signal name by the text with eyes. It is judged whether the temporary area SVP is the last signal of the connection table or not (Step 2404). When it is not judged that the temporary area SVP is the last signal of the connection table, the next temporary area SVP in the correspondence table is taken out (Step 2405), the above processing will be repeated until when it is judged that the temporary area SVP is the last signal of the connection table in Step 2404, and then the processing will be stopped.
The above two text generating methods may generate a text at the position inefficient in doing the work of the post-processing. In case of the text generating method shown in FIG. 24, the graphic table is retrieved with respect to all the corresponding temporary areas SVPs within the correspondence table and a text is generated on the coordinates of each origin of all the retrieved temporary areas POLS. Accordingly, texts may overlap with each other depending on the shape of a graphic, with the difficulty in their recognition, or the data amount may be extremely increased depending on a text. As a technique for making a text easy to see, there is a technique disclosed in, for example, Japanese Patent Laying-Open (Kokai) No. Heisei 4-227588, entitled "Graphic Data Output Device". This publication discloses a technique for making a text easy to see by revolving the text which is difficult to see because of overlapping with the other, the technique comprising text extracting means for extracting a text overlapping with another text, frequency measuring means for measuring the frequency that a text overlaps with another text, at every possible angle of the overlapping text, and angle changing means for changing the angle of the overlapping text to the angle having the minimum frequency. Although the conventional technique can make a text easy to see, which is difficult to see because of overlapping with another one, it is not to solve the problem that a text doesn't exist at the position where a viewer can see it easily and it is impossible to generate a text at the position efficient in doing the work of the post-processing.
As mentioned above, the conventional text generating method of the layout editor may generate a text at the position where a viewer cannot see it easily, thereby making it difficult to recognize the text.
When a text is generated on the whole graphics each having a signal name, the necessary data is extremely increased in the amount and the time spent in the data access also becomes enormous.
These two defects will become a further problem for the work of the post-processing after the text generation because a text is not generated at the proper position.